This is an optional Lynx Heli Main Shaft Bearing & Thrust Bearing Block Set, and is intended for use with the Align T-Rex 700. This bearing block has been re-designed to provide perfect main shaft alignment and a more rigid design in the 3 axis with free rotation thanks to a special stainless steel, ABEC-3 precision bearing and thrust bearing. This provides a more rigid frame for precise and responsive 3D maneuvers, longer bearing life, reduced noise, and better efficiency for hard and intense 3D flight. Anyone can make parts - Lynx Heli Innovations offers solutions that work!